This invention relates to skin packaging, and more particularly to skin packages and methods of making the packages.
As is well known in the art of packaging, a skin package is one made by placing an article on a substrate (e.g., a piece of paperboard) which is adapted to have air drawn therethrough for the skin packaging operation, heating a thermoplastic wrapper to a temperature such as to place it in condition for being drawn over the article and vacuum-drawn into contact with the article, and for being thermally bonded (i.e., heat-sealed or fused) to the substrate, draping the heated wrapper over the article, and drawing it against the substrate and around the article by drawing a vacuum through the substrate. The wrapper becomes like a skin on the article and substrate. Reference may be made, for example, to U.S. Pat. No. 3,031,072 showing such a package and method, and referring to use of polyolefin film (and particularly polyethylene film) for the wrapper.
The above-described skin packaging technique has been highly successful and extensively used for packaging relatively small and light-weight articles. It has heretofore been relatively uneconomical and impractical, however, to apply the technique to the skin packaging of high-profile articles which require a relatively deep draw and which are relatively heavy, requiring extra-firm confinement of the article on the substrate to prevent it from tipping over. Here it may be observed that if film which is relatively thin to begin with is used (for economy not only as to amount of film used but also to avoid prolonged heating time for the film), the film may be thinned to such an extent on account of the deep draw that the package may be weak and the article (depending on its shape) may be easily tipped over on the substrate. On the other hand, if thick film is used to avoid the problems arising from the use of thin film, the amount (poundage) of film required and/or the time required to heat the film to the softening point for the drawing operation may exceed economical limits. It has also been impractical in certain instances to apply the technique to the skin packaging of articles which are of such shape as, in effect, to have an undercut or undercuts in their position as placed on the substrate, the impracticality being due to the film being drawn into the undercut or undercuts, and being thinned down to such an extent as unduly to weaken the package. An example of an article which presents such undercuts is a cylindrical article laid on its side (rather than on one end) on the substrate.